(a) Technical Field
The present invention relates to a direct drive motor for driving a wiper arm directly connected to a motor shaft. More particularly, the present invention relates to a direct drive motor for a vehicle wiper system, which includes a clutch for restricting the movement of the motor shaft.
(b) Background Art
Generally, drive sources mounted in a vehicle to drive a vehicle wiper include a general DC motor with a four-bar linkage structure and an electronically controlled DC motor with an improved cowl package.
The general DC motor has drawbacks in that, since a motor shaft is rotated 360°, a brush provided in the inside thereof is easily worn away, and its durability and noise, vibration and harshness (NVH) performance are deteriorated.
Moreover, the electronically controlled DC motor also has drawbacks in that its durability is deteriorated due to abrasion of a brush, although the abrasion is somewhat reduced since the motor shaft is rotated 180°.
According to the above-described conventional motors with the linkage power transmission mechanism, it is impossible to achieve a precise control due to the linkage operation by a simple mechanical mechanism and its efficiency is deteriorated due to loss by a lot of mechanical joints.
Contrarily, a direct drive motor in which a driving force of a motor shaft is directly connected to a drive unit has advantages in that, since rotational inertia is minimized by a low-speed motor, it is possible to achieve a precise control, and its efficiency is improved with a configuration in which mechanical joints are minimized.
Moreover, since the above direct drive motor is a brushless motor, its durability and noise, vibration and harshness (NVH) performance are improved.
However, the direct drive motor has a drawback in that, since it does not include a means for preventing the motor shaft from moving to forcibly fix the motor shaft, if an external force is applied to a wiper arm, a rotor is rotated and thus a wiper is moved.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.